[R] Date Not Staying in Date Format

David Randel davidr00 at hotmail.com
Mon Jan 30 21:51:54 CET 2006

I have a column in a data frame that has a class of "Date" and a mode of 
"numeric".  When I:


My output stays in Date format, i.e. "2006-01-03".

However, when I run the following statment:

tapply(df$Date, df$SomeFactor, max)

my output looks like this:  9129   9493   9861  10226  10591  10956  11320  
11687  12052  12417

The returned object is of mode "numeric" and class "array".  Each array 
element is of mode "numeric" and class "numeric".  I believe that this is 
the integer representation of my date.  I can't seem to convert it back to a 

How do I get these to be intrepreted as a date instead of a number?

~Dave R.

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